This invention relates generally to the field of drug delivery, and in particular to the pulmonary delivery of powdered medicaments. More specifically, the invention relates to techniques for extracting powdered medicaments from receptacles during the aerosolizing process.
One promising way to deliver various drugs to a patient is by pulmonary delivery where a drug dispersion or aerosol is inhaled by the patient to permit the active drug within the dispersion to reach the distal or alveolar regions of the lung. Pulmonary drug delivery has shown to be particularly promising because certain drugs have been found to readily absorb within the blood circulation. For example, pulmonary delivery may be a useful approach for proteins and polypeptides that are difficult to deliver by other routes of administration.
A variety of techniques have been employed to deliver drugs to the lungs including liquid nebulizers, metered dose inhalers, and the like. Of particular interest to the invention are dry powder dispersion devices that are able to aerosolize powdered medicaments for inhalation by the patient. Exemplary apparatus for aerosolizing powdered medicaments are described in U.S. Pat. Nos. 5,458,135, 5,775,320, 5,740,794, 5,785,049, and 6,089,228, and copending U.S. patent application Ser. No. 09/312,434, filed Jun. 4, 1999, Ser. No. 60/136,518, filed May 28, 1999, Ser. No. 60/141,793, filed Jun. 30, 1999, and Ser. No. 09/583,312, filed May 30, 2000, the complete disclosures of which are herein incorporated by reference.
At least some of the apparatus described in the above references utilize a high pressure gas stream to draw the powder into an extraction tube where the powder is deagglomerated, entrained in the high pressure gas stream, and exits as an aerosol suitable for inhalation. In some cases, such apparatus may utilize a receptacle that has a penetrable lid. The extraction tube is inserted through the lid and a vent is also formed in the lid. The high pressure gas stream then draws air through the receptacle and into the extraction tube. The air drawn through the receptacle extracts the powder where it joins with the high pressure gas stream to form the aerosol. The powder is deagglomerated by the high shear forces in the gas flow.
This invention is related to alternative ways to extract powder from receptacles that store the powder.
The invention provides apparatus and methods for aerosolizing powders for subsequent inhalation. Such powders may conveniently be sealed within a cavity of a receptacle until ready for aerosolization. According to one method, an access end of an extraction tube is inserted into the cavity, and an inlet opening is also formed in the receptacle. A pressurized gas at high velocity is flowed through the inlet opening, through the cavity and through the extraction tube to move the powder in the cavity into the extraction tube where the powder is entrained in the gas to form an aerosol. The high velocity gas stream assists in scouring sides of the cavity in order to facilitate removal of the powder. The high velocity gas stream also produces a mechanical impulse against the walls of the receptacle, freeing the film of powder with a xe2x80x9cflickxe2x80x9d.
In one aspect, a seal is produced between the receptacle and the extraction tube. By permitting the pressurized gas to enter the cavity only through the inlet opening, substantially all of the entering gas flows into the extraction tube along with the powder within the cavity. In some cases, multiple inlet openings may be formed to permit the pressurized gas to flow into the cavity from multiple locations. In a similar manner, multiple outlet tubes may be inserted into the cavity to extract the powder from multiple locations. In a further aspect, the gas may be pressurized to a pressure in the range from about 1 psi to about 300 psi.
In another aspect, the inlet opening may be formed by piercing the receptacle with an access end of an inlet tube. In this way, the pressurized gas may be flowed through the inlet tube and into the cavity. Conveniently, the pressurized gas may be stored within a container. In this manner, the pressurized gas may be released from the container to permit the pressurized gas to flow through the inlet opening. In one aspect, the container may comprise a cylinder, and a piston may be moved within the cylinder to produce the pressurized gas. Alternatively, the gas source may be a liquefied gas which is introduced into the receptacle where it vaporizes. In one particular aspect, the aerosol may be captured in a capture chamber where it may be inhaled by a patient.
In another embodiment, the inlet opening is formed in the bottom of the cavity such that the hole is generally aligned with the access end of the extraction tube. A pressurized gas is then flowed through the inlet opening in the bottom end of the receptacle and then through the extraction tube to move the powder in the cavity into the extraction tube where the powder is entrained in the gas to form an aerosol. Optionally, the receptacle may be configured as described in copending U.S. application Ser. Nos. 60/172,317, filed Dec. 17, 1999 and 09/731,318, filed on the same date as the present application, the disclosure of which is herein incorporated by reference. For example, the receptacle may include a raised central region that extends upwardly into the cavity and is generally aligned with the extraction tube.
The invention further provides an apparatus for aerosolizing a powdered medicament. The apparatus comprises a housing for holding a receptacle having a cavity that holds a powder. A hole is provided in the housing to form an inlet hole in the receptacle. Further, at least one extraction tube is provided for placement into the cavity. The apparatus further includes a pressure source to provide a pressurized gas into the cavity through the inlet hole to permit the pressurized gas to flow through the cavity at a relatively high velocity and then through the extraction tube. In so doing, the pressurized gas moves the powder in the cavity into the extraction tube where the powder is entrained in the gas and deagglomerated by the large shear forces to form an aerosol.
In one aspect, the hole forming mechanism comprises at least one inlet tube having an access end that is adapted to pierce the receptacle. Further, the pressure source is coupled to the inlet tube. Seals may be formed between the receptacle and the inlet and extraction tubes so that gases may only enter into the cavity through the inlet tube and may exit only through the extraction tube.
In another aspect, the pressure source comprises a cylinder, and a piston that is slidable within the cylinder. A valve is utilized to release the pressurized gas from the cylinder. The pressurized gas may be at a pressure in the range from about 1 psi to about 300 psi.
In yet another aspect, the extraction tube may have an access end that is adapted to pierce the receptacle. Further, a capture chamber may be coupled to the housing to receive the aerosol. The capture chamber may include a mouthpiece to permit the aerosol to be inhaled. In one aspect, the capture chamber may include a vent with flap valve to permit gases to enter into the capture chamber as the aerosol is inhaled.
In another embodiment, the housing may include a holder for holding the receptacle. The piercing mechanism may be configured to pierce an inlet opening in a bottom end of the receptacle. With this configuration, the extraction tube may be placed into the cavity so as to be spaced above the bottom end of the receptacle and to be aligned with the opening in the bottom end. In this way, the pressurized gas may flow through the inlet opening in the bottom end of the receptacle and into the extraction tube to move the powder from the cavity and into the extraction tube where the powder is entrained in the gas to form an aerosol.